The present invention relates to automatic transmissions and, more particularly, to improvements in a planetary carrier assembly for General Motors 4L60, 4L60E (hereinafter “GM transmissions”) and other similar transmissions.
Planetary gears are so-named because of their physical arrangement. That is, a planetary gear set consists of a so-called sun gear positioned within an internal ring gear and a planetary carrier assembly, which contains and supports the smaller planet gears called pinions. Planetary gear sets are used in the GM transmissions as the basic means of transferring the torque and power of the engine to the drive wheels. The planetary gear set allows speed and directional changes in the automatic transmission without disconnecting the engine from the drive wheels with a clutch, as with a manual transmission. The GM transmissions include two planetary gear sets, namely, the input and rear reaction gear sets, which are provided in both four and five pinion gear configurations.
The planetary gears are designed so that several gear teeth are always in mesh at once. This design distributes the mechanical forces over several gear teeth for added strength and prevents any damage associated with gears going in and out of mesh. The planetary gears include helical teeth, which impart axial thrust to the sun gear upon shifting into different gear ranges. Accordingly, in the planet carrier assembly a thrust bearing such as a Torrington radial roller bearing is employed to distribute this axial thrust force.
However, in the original equipment manufacture (hereinafter “OEM”) planet carrier, the maximum size and corresponding load rating of the thrust bearing is limited by the physical diameter of the central opening in the carrier, which provides the only access for installation of the thrust bearing. As a result the OEM thrust bearing has a high failure rate, which causes shifting malfunctions and can result in catastrophic failure of related components. Thus, the present invention has been developed to resolve this problem and other shortcomings of the prior art.